Engine downsizing includes reducing engine displacement and quantity of engine cylinders to reduce weight, friction and pumping losses, while increasing engine operation in high-speed, high load operating regions to maintain performance in terms of power and efficiency. Known downsized engines employ intake air compressors to boost airflow, affecting engine knock and exhaust emissions. One known engine control strategy to reduce knock includes retarding combustion phasing by controlling spark ignition timing, with a corresponding decrease in engine efficiency. One known engine control strategy to manage NOx emissions includes operating at increased cylinder dilution with recirculated exhaust gas, with a corresponding risk of reduced combustion stability.